The steam boiler’s steam generation pressure can be lower than the design pressure, but is there a minimum requirement for steam generation pressure?
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Our gas steam boiler, with a capacity of 4 T/h, is designed to produce 7 kilograms of steam, which is then reduced in pressure using a pressure regulator to 4 kilograms for use in heating process equipment and HVAC systems. The customer asked: Why can’t the boiler burn 4 kilograms of steam directly, thereby eliminating the need for a pressure reduction device? Is there any document that specifies the recommended operating pressure for boilers, as well as the relationship between the gas production pressure and parameters such as boiler efficiency?
Operating the boiler at low pressure cannot ensure a stable supply of steam to the process equipment; moreover, low-pressure steam has a high water content and low calorific value, failing to meet the steam requirements of the process equipment.
It’s a simple principle: if the boiler burns 4 kilograms of fuel directly, fluctuations in load will affect the steam pressure, and the boiler’s ability to adjust its load is relatively slow
4 kilograms of steam are sufficient to meet the heat exchange requirements of process equipment, as well as those for heating, ventilation, and hot water systems. That’s why the customer asks me this question. I can’t find any documents or more official materials to respond to him.
The use of a pressure relief valve device is to ensure the safety of process equipment.
Just use 0.4 MPa – what’s the problem with that? It’s easy for the boiler operators as well – they just need to set the pressure switch to 0.42 MPa; an alarm will be triggered if the pressure exceeds this level.
Sure, we originally planned to use boilers for power generation; at first they were not used for generating power but instead produced low-pressure steam for external supply； Later, the steam pressure was increased to generate electricity
It is planned to burn 7 kilograms of steam, and then use a pressure reducer to reduce the pressure to 4 kilograms for heat exchange in process equipment and HVAC systems. . . The key here is the process equipment – are there any temperature requirements? As for HVAC equipment, it doesn’t matter. If there are no temperature requirements in the process, it can operate at 0.4 MPa.
The process equipment has no temperature requirements. Steam is used for indirect heat exchange, and no particularly precise temperature or pressure is required; typically, in the heat exchangers found in light industrial facilities, the steam side is set at 3-4 kilograms. If a 7-kilogram steam boiler is used to burn only 4 kilograms of fuel, and if the load at the end point varies significantly and remains unstable, can the boiler’s burner and exhaust pressure still be adjusted accurately in response to such changes in load? Could there be frequent starts and stops, resulting in overpressure that causes the safety valve to activate repeatedly? (Because the heating surface area of the boiler is designed for 7 kilograms, but now only 4 kilograms are being used,)?
When the end load changes, can adjustments such as those to the boiler burner and exhaust pressure still be carried out accurately? Could there be frequent starts and stops, resulting in overpressure that causes the safety valve to activate repeatedly? ......Calculate how much the load at the end changes, and determine whether it is intermittent heat exchange; if it is not intermittent heat exchange, then gas outlet pressure adjustment is possible ； The preliminary solution to the problem of repeated activation of the safety valve due to overpressure is to adjust the safety valve to its original design setting of 7 kilograms, thereby reducing the operating pressure to 4 kilograms.
"If it is not intermittent heat exchange, the outlet gas pressure can be adjusted. \"Why can’t the outlet gas pressure be adjusted in the case of indirect heat exchange?\" It’s indirect heat exchange, so can’t the pressure be adjusted? I didn’t understand.